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By Wang Xuewen, Bao Qingbao, Xie Jiacheng, Yan Zewen

This study puts forward a virtual memory cutting method based on the prediction of AFC shape. The integrated key technologies include the generation of virtual teaching cutting curve, the height adjustment strategy of front and rear drum, cutting height adjustment strategy, the reciprocating cycle of cutting technology and so on. Through the two algorithms, SVM and ELM, the form of the next working cycle can be obtained by rolling prediction using the form information of AFC in the first several circulations. Based on the obtained dynamic fluctuation of the form in the vertical and horizontal working faces, the position and cutting information of the shearer during its operation can be controlled and predicted in advance, the memory cutting template can be adjusted and modified in time. Employing this method, the more stable, accurate and timely memory cutting of the shearer under the uneven coal seam could be realized.

Aug 16, 2021

By James J. Komadina

INTRODUCTION Newmont Gold Company's Rain operations are located in Elko County, Nevada, approximately 9 miles southeast of the Town of Carlin.The property was submitted to Newmont Exploration Limited in 1979 and underwent development drilling over the course of the next four years, culminating in the completion of a project feasibility study in October 1986. Initial project scope included development of an open pit mine, an 815,000 DSTPY heap leach, a 572,000 DSTPY mill (Mill No. 3), and associated support facilities. Approval to proceed was given by Newmont Gold Company management in June 1987. Detailed engineering began in early July, followed immediately thereafter by procurement of major equipment components through various second hand sources. PROJECT DESIGN Keep It Simple In early August, Newmont Mining Corporation, parent company of Newmont Gold Company, became the takeover target of an "investor" group headed by T. Boone Pickens. Details of the ensuing events have been well documented by the press; suffice to say their impact on this project was material and required immediate flowsheet changes. Project design throughputs were increased to 1,000,000 DSTPY and 760,000 DSTPY for the heap leach and mill, respectively, in mid- September. These changes caused major project headaches as all general arrangement drawings had been approved and structural steel as well as concrete contracts were in place. Additionally, ground breaking was to commence in two weeks time! Rain project management assembled shortly after the announced changes, to devise an engineering and construction strategy capable of handling these new business conditions. The project had been justified using a gold price of $325 per ounce with a forecasted overall cash cost per ounce of $230. Hence, strict control of capital expenditures was necessary to maintain development economics. Mill start-up had also been moved forward one month, to August 1, 1988. To meet an already ambitious schedule, construction techniques needed to be simple and proven as most of the facilities were planned for erection during winter at a site with design criteria of -40F and 90 mile per hour winds. Perhaps the most critical factor requiring consideration was that of personnel. Newmont Gold's revised business plan called for corporate-wide production increases from 587,000 ounces per year in 1987, to 1,400,000 ounces by mid- 1989. Labor requirements were forecasted to grow from 900 employees to over 2,100. This fact, in combination with the rapid growth of Nevada's gold industry, led to the expectation that turnover of operating personnel would be extremely high. It was concluded that, to meet cost, time, and operational goals, the necessary strategy could be succinctly put - "Keep It Simple." Mining/Metallurgical Factors The Rain deposit consists of three interconnecting mineable shapes with host rocks ranging from 90%+ barite to a highly silicified jasperoid. Due to a limited number of mining faces in the first two years, in-pit blending

Jan 1, 1990

By Sandeep Kumar Asarapalli, Sunil Kumar Bisoyi, Bhatu Kumar Pal

Spontaneous heating of coal is one of the major concerns in the coal mining industry. Hundreds of millions of tons of coal are lost each year because of spontaneous heating. If necessary arrangements are made, many fires due to spontaneous heating may be avoided. Therefore, protective measures have become essential to prevent coal from spontaneous combustion. A large amount of coal reserve can be saved by the assessment, suppression, and prediction of spontaneous heating of coal, which also helps in betterment and efficient coal production. The use of chemical retardants can act as inhibitors for the liability of coal toward spontaneous heating by increasing its ignition temperature, thereby, increasing its incubation period. The coal-chemical mixture can be used for whitewashing the exposed coal in galleries as it creates a layer between coal and oxygen in the atmosphere, delaying the oxidation process and ultimately inhibiting the spontaneous heating liability of coal. This work examines the effect of chemicals such as sodium chloride, calcium carbonate, potassium iodide, sodium nitrate, and potassium chloride on the spontaneous heating of a coal sample. Thereby, it suggests a better chemical for inhibiting the liability of coal toward spontaneous heating. The experimentation involves flammability temperature (FT), crossing point temperature (CPT), and differential thermal analysis (DTA). The ignition and oxidation temperatures were found from the above experimental methods for Lingaraj open-cast coal mine samples, with and without adding chemicals. The results are cross-checked and verified through DTA. Correlation analysis was carried out among the results obtained from CPT, DTA, and FT, and better chemical retardants that effectively inhibit coal’s tendency toward spontaneous heating were suggested.

Dec 23, 2023

By J. A. Rusnak, K. M. Mohamed, M. A. Van Dyke, M. M. Sears, G. Rashed

"Researchers from the National Institute for Occupational Safety and Health (NIOSH) recently developed a coal-mass model to realistically simulate the deformation and loading behaviors of the ribs of coal pillars in underground coal mines. The scale-dependent properties (stiffness and strength) of coal material were considered in the coal-mass model. In this paper the orientation of face cleat with respect to driving direction was integrated in the coal-mass model. The controlling parameters (dimensionless coal-mass scale and fracture strains) of the modified coal-mass model were calibrated using a published case study of coal pillar strength. Numerical models with wide ranges of controlling parameters were conducted to simulate the test pillar. The best match between the numerical modeling results and the measured stresses and deformations was achieved by using a coal-mass scale of 30 and fracture plastic shear and tensile strains of 3.25% and 0.325 %, respectively. INTRODUCTION The failure of coal pillar ribs by itself are a major hazard in underground coal mines. Furthermore, failing ribs can indirectly contribute to roof and floor instability by increasing opening widths across intersections and entryways. Over the past decade, rib failures have resulted in 12 fatalities, representing 28% of the ground-fall fatalities in U.S. underground coal mines. Mining depth has always played a very important role in assessing rib stability. Gauna and Mark (2010) completed an analysis of rib fatalities that occurred between 1996 and 2010. One of their most prominent and influential findings was the identification of a relationship among fatalities, depth, and mining height. Therefore, Coal rib stability will continue to be a challenge for future deeper mines in U.S. coal basins. In the past several decades, research efforts have focused on roof support. The current rib control practice in U.S. coal mines is to select rib bolts through a trial-and-error approach (Mohamed et al., 2015a). Rib failure incidents can be can be substantially reduced or even eliminated by adopting an engineering-based coal rib design approach. The factors affecting rib stability in coal mines are numerous and mutually dependent. These factors include but not limited to mining height and overburden depth, interburden thickness for multiple-seam mining, coal strength, cleat density, entry direction with respect to cleat orientation, existence or absence of partings in the coal, percentage of extracted roof and/or floor rock, density of rib bolt support (Mohamed et al., 2015a). Moreover, it is difficult to isolate the particular effect of a specific factor on the overall rib stability. Therefore, a reliable empirical rib design approach is not achievable because it requires a significant number of case histories to be collected in order to have a reasonable range of all of the critical parameters. However, numerical modeling can be a practical tool to assist with rib support design if the modeling is realistic, which can only be achieved through calibration and validation of the numerical model against field data."

Jan 1, 2018

By Laura Suarez, Jörgen Kajberg, Pär Jonsén

How does an investigation into the breakage characterization of electric arc furnace (EAF) manganese slags contribute to a more responsible usage of resources throughout the life cycle of steel products and reduction of carbon emissions? The main goal of this study is to increase the knowledge on the mechanical response of manganese slag to open the potential of pyrometallurgical residues to become secondary material in industrial applications such as infrastructure construction, fillers, binders and soil stabilization, among others.

Mar 1, 2024

By Akram Marseet, Andrew J. Petruska, Rik Banerjee

Underground mine roof bolting is a crucial operation for miners’ safety and mine sustainability. Since roof bolting is a manual or human-supervised operation, miners’ safety is at risk due to dust or rock falls. Traditional machine learning algorithms have shown limitations to detecting drillable areas, mainly due to harsh lighting conditions. The authors propose an adaptive deep-learning framework for autonomous roof bolting. The proposed framework is based on implementing a binary semantic segmentation algorithm on color images to classify pixels that belong to rock from those that belong to non-rock. Significantly, the proposed framework implements deep learning semantic segmentation on images from traditional and neuromorphic vision sensors in underground mines. The performance of the proposed model shows an impressive accuracy level of at least 98% at a low number of training epochs with smooth learning curves. The high accuracy enables the implementation of autonomous roof bolting, greatly improving miners’ safety and operational efficiency while reducing human exposure to safety hazards. This research will advance the use of deep learning in mining automation and has the potential to revolutionize the traditional mining industry.

Feb 1, 2024

By R. Casagrande, L. R. Moore, J. Sessoms, P. Macy

"A South American nickel mine has been producing a nickel concentrate that also contains copper and iron (15 percent nickel, 5 percent copper, 28 percent iron) for the end use of stainless steel production. A critical specification for the quality of the steel is the iron to magnesium oxide ratio (Fe:MgO), with a ratio of below 3.5:1 having a substantial impact on the nickel value. This nickel concentrate producer historically mined the sulfur-rich mineral pyroxenite but had been forced to move to a magnesium oxide/silicate (MgO/SiO4)-rich mineral harzburgite, resulting in nickel recovery being reduced to around 50 percent to maintain the required Fe:MgO ratio. In this study, ore mineralogy, water chemistry and the chemistries associated with the flotation process were evaluated in an effort to increase nickel recovery while maintaining the Fe:MgO ratio according to specification. New chemistry was introduced with the specific goal of complexing with the MgO and retarding its interaction with the bubble flow in the flotation process.IntroductionGlobal nickel production in 2011 totalled to 1,770,000 tons, according to the Raw Materials Group (2013). From 1950 to 2005 there was an aggregate 4.4 percent increase in nickel production, with a market-value high of $1,000/ton nickel reached in 1998 (Mudd, 2010). Approximately 65 percent of nickel production is consumed by the stainless steel industry, with 12 percent of the remainder used in super alloys or nonferrous alloys. Nickel imparts corrosion resistance, temperature resistance and other benefits to its alloys (Table 1) (Oberg, 1996; Cáceres, 2003). The dominant types of nickel-bearing ores are classified as either laterites (limonite: nickel-iron oxide; and garnierite: nickel hydrosilicate) or magmatic sulfide deposits (pentlandite: iron-nickel sulfide) (U.S. Geological Survey, 2013a, 2013b). In 2012, about 40 percent of the nickel ore mined was sulfidic-type ores and about 60 percent was laterite. The processing of laterite ore is expected to continue to increase as the availability of sulfidic ores continues to decline."

Jan 1, 2015

By R. Benemelis

The existence of resins in some coal deposits in various parts of the world has been known for many years. These resins vary considerably in chemical structure and properties. The resin that is found in Utah coal, however, is rather unique, and has properties particularly attractive for the manufacture of printing ink mastics and adhesives. This resin is a rather dark, very high melting point, low molecular weight hydrocarbon resin. Its typical properties are shown in Table I. Its largest use by far, has been in the printing ink industry. The history of Utah coal resin is interesting, but unfortunately one of disappointment and failure.

Jan 1, 1990

By Dan Norrgran

In recent years, a great deal of attention has been focused on developing mill liners to increase wear resistance, improve grinding efficiency and reduce energy consumption in milling applications. The installation of an appropriate mill liner is critical as it affects the overall cost and product quality. A mill liner has two specific functions. The first is to protect the mill shell and mill ends from direct contact with the abrasive grinding media (in this case, the liner serves as a wear surface). The second function is to transport the grinding media, creating energy for size reduction. The liner acts as a lifter, mechanically transporting and cascading the grinding media. The mill lining is a major cost in the milling operation. The costs associated with the mill lining include the capital cost of the lining, downtime required to replace the worn liner and the labor for installation. Generally, in hard rock mining, the life of a mill liner in secondary ball mills is 12 to 24 months.

Jan 1, 2009

By Jr. Schnakenberg

In 1986 the U. S. Bureau of Mines (USBM) embarked on a major research effort to develop technology that can substantially reduce worker exposure to face hazards simply by relocating the equipment operators to an area of relative safety. This reduced exposure mining system (REMS) research effort enhances the USBM ongoing health and safety research efforts to reduce and control dust and noise and to reduce accidents through training and better mining practices. This paper reports progress of the research that is developing and will demonstrate the technologies required for the computer-assisted tele-remote operation of continuous mining machines, haulage systems, and roof bolting machines.

Jan 1, 1996

By Bruce E. Kester

The concurrent observation of the phenomena of alkali-aggregate reaction and development of efficient dust collection systems on rotary kilns made mandatory the process modifications to produce low alkali cements. Such low alkali cements as were available prior to these recent changes were either the rare result of low alkali raw materials, the loss of alkalies with dust loss from the kiln stack, or in some instances by the use of CaC12 in the kiln feed to increase volitalization of the alkalies and their subsequent loss or discard with the normal dust emission from the kiln. The relative slowly soluble nature of natural occurring alkali minerals in cement raw materials as compared to the very soluble nature of the alkali salts as present in cement kiln reaction products, either in clinker or in dust emission led to the development of the water leaching system. Two distinctly different problems of leaching are created by the two major systems of portland cement production, the wet and dry processes. The wet process is characterized by moderate dust loads and concentration of soluble forms of alkali in the dust. Further the return of the leached dust slurry does not materially change the characteristics of kiln feed on reintroduction and subsequently does not materially influence kiln operation. The dry process differs in high levels of dust emission and the presence in the collected dust of large amounts of unreacted kiln feed with its sparingly soluble alkali minerals. In the dry process reintroduction of leached dust slurry changes the dry process to what may be classed as a damp process. This change results in some decrease in kiln capacity and creates conditions of operation which are uncommon to either the wet or dry process.

Jan 1, 1963

By J. A. Organiscak

The National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) has recently studied several redirected scrubber discharge configurations in its full-scale continuous miner gallery for both dust and gas control when using an exhaust face ventilation system. Dust and gas measurements around the continuous mining machine in the laboratory showed that the conventional scrubber discharge directed outby the face with a 12.2-m (40-ft) exhaust curtain setback appeared to be one of the better configurations for controlling both dust and gas. Redirecting all the air towards the face equally up both sides of the machine increased both the dust and gas concentrations around the machine. When all the air was redirected towards the face on the off-curtain side of the machine, gas accumulations tended to be reduced at the face at the expense of increased dust levels in the return and on the curtain side of the mining machine. A 6.1-m (20-ft) exhaust curtain setback without the scrubber operating resulted in the lowest dust levels around the continuous mining machine, but this configuration resulted in some of the highest levels of dust in the return and gas on the off-curtain side of the mining face. Two field studies showed some similarities to the laboratory findings, with elevated dust levels at the rear corners of the continuous miner when all the scrubber exhaust was redirected towards the face either up the off-tubing side or equally up both sides of the mining machine.

Feb 23, 2014

By P. K. Sollars, M. A. Alspaugh

In May of 1996, Twentymile Coal Co. began Longwall mining in the Foidel Creek Mine's East Mine District. These Longwall panels are some of the longest in the world (5.48 km/18,000 ft) with very difficult and challenging geometry. The conveyance system is 1,800 mm (72 in) wide, has a 4,500 mtph (5,000 stph) capacity and employs multiple tripper drives. The trippers include traditional powering designs as well as unique regeneration and braking designs. Several components were developed specifically for this application including a mobile tail brake. Control algorithms were carefully developed and tested via computer modeling. A world production record was achieved in the third month of operation and over 1 million tons were mined in June 1997.

Jan 1, 1998

By James F. McConnell

Federal and State sulfur oxide emission and ambient air quality regulations have been implemented to fulfill the requirements of the Federal Clean Air Act Amendments of 1970. Primary and secondary air quality standards have been established at levels considered necessary to assure the protection of the health and welfare of the public. Standards of performance under this Act have been established to control the rate of sulfur oxide emissions from individual sources so as to protect and to improve the quality of the Nation's air. The new source standards of performance were made rigorous for large coal burning stationary sources. This has had a severe impact on the electric utilities that operate the coal fired steam electric plants which are the largest consumers of the Nation's coal production. States have taken different approaches in State Implementation Plans (SIPS) as approved by the Federal Environmental Protection Agency. Some states, such as Pennsylvania, have chosen to permit moderate SO2 emission rates from existing sources which are not in critical air basins. All are required to meet primary and secondary air quality standards and to limit sulfur oxide emissions from new large stationary sources to a minimum of 1.2 LBS of S02/MMBTU fired. This re- quires a fuel sulfur percentage of about 0.7 for a 12,000 BTU/lb coal. In an effort to develop strategies and technologies to conform to performance standards while continuing and hopefully expanding the utilization of the Nation's coal supply, the electric utilities, the Federal and State regulatory agencies, and other industries and government agencies are considering several alternatives. 1. Natural low sulfur coal 2. Flue gas desulfurization - (FGD) non-regenerative and regenerative 3. Coal gasification 4. Liquefaction and solvent refined coal 5. Fluidized bed combustion 6. Chemical coal cleaning 7. Physical coal cleaning Of these options, only the first and the last can be considered to be widely used in full commercial practice at this time. FGD has certainly demonstrated technical and operating feasibility and is close to being in full commercial practice but it remains to be seen if the large systems under construction are economically and environmentally optimum.

Jan 1, 1975

By W. Gibson Jaworek

Of increasing importance to the student of fuels economics has been the extent to which different primary energy sources can substitute for each other in the various energy markets of the nation. Knowledge of the nature and extent of fuel interchangeability can aid the fuels economist in projecting trends of energy utilization, as well as giving him a better understanding of the past and present conditions of fuel markets. It is also important to the consumer to know just how much flexibility he can maintain in his energy consuming operations. And, finally, various governmental bodies show keen interest in the degree of energy substitutability in determining public policies concerning the fuels industries. The presence of excess fuel production capacity in the United States during the early 1960's indicates that fuel interchangeability should become more prevalent in the increasingly competitive energy markets of the nation. Discussion of fuel intercompetition is almost always restricted to qualitative terms-because of the lack of comparable statistical data, between the different energy sources in geographic or "type-of-use" fuel, markets. There are exceptions, of course, such as, the excellent fuel consumption data which are available on steam electric generating plants throughout the nation. In other sectors, statistics are at best incomplete.' Inmost instances, indirect fuel consumption indicators, such as sales of fuel burning equipment, are extensively used to measure market shares of a particular fuel; however, these indicators are hard to evaluate precisely without prior knowledge of the total competitive market.

Jan 1, 1961

By Raymond E. Zimmerman

The use of standard dense-media cyclones is well known, as they have been in use for many years. They are especially well suited for operating at low separating densities and for treating difficult coals containing a high percentage of near-gravity at the point of separation. Very few modifications of the basic design have ever been made. The author recently, however, has been interested in the development of a new type of dense-media cyclone that has been produced in Japan. He has observed the testing of this unit and has collected much data which he feels should be of considerable interest to coal preparation engineers. He feels that this unit, called the Swirl Cyclone, may be of substantial value as an alternate to the standard cyclones. It is certainly worthy of further investigation. There has been relatively little written in English-language publications on the Swirl Cyclone. It was briefly described at the Fifth International Coal Preparation Congress. I It has been described in a general manner by the author in two prior publications. 2, 3 This paper proposes to describe this device in more detail and at the same time submit technical data illustrating its wide characteristics.

Jan 1, 1977

By Lynn Huntsman

INTRODUCTION The Sunnyside mines of Kaiser Steel Corp. are lo¬cated on the west flank of the Book Cliff Range, a tongue of the Wasatch mountain range in Utah. The mines are 193.12 air km (120 air miles) southeast of Salt Lake City and 40.23 km (25 miles) east of the town of Price. The area has a semiarid climate with an an¬nual rainfall of 304.8 to 381 mm (12 to 15 in.) and a temperature range of -23.3 to 32.2°C (-10 to 90°F). The base of the Book Cliff Range is approximately 1981 m (6500 ft) in elevation with some mountain peaks in excess of 3048 m (10,000 ft) (Fig. 1). The Sunnyside mines were opened in the late 1890s and have been operated continuously since that time. Kaiser Steel leased the No. 2 mine in 1942 and pur¬chased the entire property in 1950. There are three mines adjacent to one another, each with its separate access, ventilation, and haulage. The three mines en¬compass an area extending 12.87 km (8 miles) along the outcrop and dipping northeasterly 2.41 to 3.22 km (11/z to 2 miles) into the Book Cliffs. During 1975, only the No. I and No. 3 mines were operating to sup¬ply 908 184.7 t/a (1,000,000+ stpy) of clean coal to the Kaiser Steel mill at Fontana, CA. Sunnyside coal is blended with coal from the Kaiser Steel mine near Raton, NM, and with purchased coal from noncompany sources to form the mix for the coke ovens. At that time, Sunnyside operated three longwall units and five to seven continuous miner units. Typical production for that time came from one miner unit pillaring an area not conducive to longwall mining; one or two miner units on construction or modernization projects, and the remaining units used to develop future longwall panels. Longwall mining has been a part of the Sunnyside scene since 1961 when the first panel was set up in the lower Sunnyside seam of the No. 3 mine. Through 1975, 27 longwall panels were mined (Fig. 2). Of the more than 47 173 604 t (52,000,000 st) of clean coal that were taken from the property through 1975, 6 350 292.9 t (7,000,000 st) were mined by longwall methods. Coal was brought to the surface in 4.5-t (5-st) mine cars and crushed to -152.4 mm (-6 in.) before entering the preparation plant. Coarse coal is cleaned by Baum jigs and fine coal (-28 mesh) is cleaned in flotation cells. The coal is reduced to 50.8 x 0 mm (2 x 0 in.) and belted to an aboveground storage pile with a ca¬pacity of approximately 113 398.1 t (125,000 st). The coal is gravity fed through two 1.52-m (5-ft) diam culverts directly into railroad cars, which pass beneath the storage pile through an arched excavation. Eighty-four 90.7-t (100-st) cars make up a unit train which makes the round trip to the steel mill in four days. Additional trains are scheduled in as demands dictate. Loading rates in excess of 13 607.8 t/h (15,000 stph) have been attained. Geology The coal seams of this area are of Cretaceous age and are classed as a medium volatile bituminous coal. coal, with a sulfur content less than 1 % and 6 to (20-mile) zone of the Book Cliffs, and this area is owned or under lease by either Kaiser Steel or US Steel. Coal in adjacent areas is noncoking but an excellent steam coal, with a sulfur content of less than 1 % and 6 to 7% ash. Sunnyside coal contains 40% volatile, 53% carbon, less than 1 % sulfur, and 51/2 to 61/2 % ash after washing. There are two minable seams throughout most of the Sunnyside property known locally as the upper and lower Sunnyside. Separation between the seams varies from less than 300 mm (1 ft) near the southern boundary adjacent to the US Steel Columbia mine, to over 12.19 m (40 ft) in areas of the No. 3 mine in the center of the Sunnyside property. The upper seam varies in height from 1.2 to 1.98 m (4 to 61/2 ft) while the lower seam varies in height from 1.52 to 4.28 m (5 to 14 ft) in areas of No. I mine where the two seams apparently come together. The majority of early work was con¬centrated in the upper seam which has a stronger roof and a lower sulfur content. When Kaiser Steel began mining the No. 3 mine in the early 1950s, it mined in the lower seam beneath the old workings with conven¬tional and continuous mining equipment. Numerous bounces and pressure points created by unextracted pillars and barriers in the upper seam made this a low¬production, high-cost mine and brought about the ad¬vent of the first longwall system. The first unit, while small by today's standards, successfully mined panels that had been all but given up and saved the mine from closure. There were areas that could not even be mined by longwall because of the erratic extraction in the upper seam. The system was successful enough to allow operations to gain access to and develop virgin areas of the upper seam. Development of longwall mining in the No. 3 mine has been confined to the upper seam since late 1964. With the almost complete extraction afforded by the longwall system, it is felt the lower seam can be successfully worked in future years (Fig. 3). In most of No. 1 mine, only the lower seam (or lower seam and upper seam combined) is minable, except in the northwest portion where a rock split has again separated the seam into two 1.83 to 2.13-m (6 to 7-ft) thick beds. In this area, the upper seam or upper split is being mined. The separation between seams at the present workings in this area varies from 0.609 to 6.1 m (2 to 20 ft). It is hoped that most of the lower split can be mined using shield supports and/or what¬ever new technology is developed in the coming years. The coal seams in this area dip to the northeast at an average grade of 10%. The dip near the outcrop reaches 22% and gradually decreases downdip. Over¬burden ranges from a few meters at the outcrop to 762 m (2500 ft) over some of the deeper workings. In the next several years, some overburden will be in excess of 914 m (3000 ft) as the lower mine workings extend ever deeper under the Book Cliffs. To cope with the

Jan 1, 1982

By R. Addison

This is the story of the Carlton Mill. But first-a little geography. For those who do not know where the Carlton Mill is, or, perhaps, have only a vague idea, its location is indicated in Figure 1. The plant is situated on the road between the two old mining towns of Cripple Creek and Victor, 10 the west of Colorado Springs. From Denver, it's about 110 miles by road. The story of the Carlton Mill began with the discovery of gold at Cripple Creek in 1890. This discovery set off a major boom such that, by the turn of the century, there were 450 separate operating mines in the district. Gold production boomed early and declined rather rapidly as indicated by the graph in Figure 2. Significant factors affecting production are shown on the graph-the raising of the gold price in 1934 from $20.67 to $35.00 per ounce and the government executive order L-208 in 1942 requiring the closure of all gold mines.

Jan 1, 1983

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jonathan K. Hrica, CASSANDRA L. HOEBBEL, Jason Navoyski, Jennica L. Bellanca

Haul truck fatal accidents and injuries continue to be a significant concern for the mining industry. However, the availability of high-quality training materials continues to be limited. Near-miss incident accounts, if packaged well, could help fill this gap, because for every fatality, there are hundreds of reportable accidents and thousands of undocumented near misses. Researchers from the National Institute for Occupational Safety and Health (NIOSH) collected detailed accounts of 21 near-miss incidents in virtual interviews with mineworkers at surface mining operations across the country. From these interviews, researchers created four simulation videos using the Unity game engine. The simulation videos bring these events to life through first-person retelling and various visual perspectives of actual events. Each video exemplifies a critical safety message and a common haul truck hazard. This paper describes the process of taking narratives and turning them into impactful visual stories using graphic simulation. NIOSH plans to co-release these simulation videos with the Mine Safety and Health Administration (MSHA) to the mining industry to raise awareness and ultimately help reduce haul truck-related accidents and fatalities in mining.

Jun 1, 2023

By Lennart Bergstedt

Boliden Aktiebolag, the prime base metal mining company of Sweden, annually treats some 11-12 million tons of sulphide ore in nine concentrators. Its first flotation plant was established in the early thirties for the complex Boliden ore. Since then, the number of mines and plants has gradually increased. Considerable effort has been devoted to the development of all phases of the technology of ore prospecting, mining, milling, smelting and refining. This has been necessary due to the complex and low-grade ores. The development of concentration has mainly been directed toward the arts of grinding and flotation. During the forties and fifties, open-stage fine crushing followed by two-stage grinding in rod and ball mills with cyclone classification was successfully introduced and used throughout the plants. The increasing cost of grinding media led to studies of an autogenous grinding technique as early as 1945. Basic test work commenced during the early fifties, with a. number of ores tested for pebble grinding. In 1956 a new pilot plant was built, with equipment installed for the continuous testing of pebble grinding and, later, for primary autogenous grinding of run-of-mine ore. The intensive test work showed that pebble grinding was feasible in almost all of the plants. At this early stage of testing, however, the merits of autogenous grinding could not be fully evaluated. As a. consequence the rod mill/ball mill grinding systems were converted to rod mill/pebble mill systems whereever possible. In parallel with the converting of grinding systems the development work concerning the merits of autogenous grinding went on. The major result

Jan 1, 1977